The present invention is directed to a process for the polymerization and the copolymerization of olefins, particulary ethylene, in the presence of solid catalysts.
Belgian Pat. No. 650,679 describes a process for the polymerization and the copolymerization of olefins in the presence of a catalyst obtained by activating with an organometallic compound the reaction product of a compound of a transition metal and a solid hydroxychloride of a divalent metal. The hydroxychloride of a divalent metal is preferably magnesium hydroxychloride of the formula Mg(OH)Cl.
Though it has not yet been established, it is believed that the reaction between the compound of a transition metal and the hydroxychloride of a divalent metal to produce the catalysts described in the above Belgian patent is the result of a chemical bonding by means of the -OH groups of the hydroxychloride.
This reaction may be represented by the following equation: EQU M'X.sub.n + M(OH)Cl.fwdarw. X.sub.n-1 M'--o--M--Cl + HX (1)
where
M' represents a transition metal, PA1 X is a monovalent reactive group attached to M', PA1 M is a divalent metal. PA1 a divalent metal M, preferably magnesium, chlorine, PA1 a transition metal M' bonded to the divalent metal by means of oxygen, PA1 reactive groups X bonded to the transition metal. PA1 divalent metal M. preferably magnesium, PA1 a halogen, PA1 oxygen, PA1 a transition metal M' chemically bonded to the support, PA1 halogenated substituents, bonded to the transition metal.
THE CATALYTIC COMPLEX RESULTING FROM THE ABOVE REACTION (1) HAS BEEN REPRESENTED BY THE FORMULA X.sub.n-1 M'--O--M--Cl which accounts for the stoichiometry of the bonding reaction. However, as the compound is at least partially ionic, it is possible that the above formula does not represent exactly the structure of the resulting catalytic complex.
In any case, it is established that this catalytic complex comprises the following elements:
The catalytic polymerizations carried out with these complexes, in accordance with the above Belgian patent, have the disadvantage of requiring that the divalent metal compounds be used in the form of hydroxychlorides. These compounds, which are not commerically available, are very sensitive and are costly to prepare. In addition, the hydroxychlorides are unstable and are easily dissociable, thereby producing hydrogen chloride, according to the following reaction: EQU M(OH)Cl.fwdarw. MO + HCl (2)